Wood stains containing a flavanone azo dye and brightener



United States Patent WOOD STAINS CONTAINING A FLAVANONE AZO DYE AND BRIGHTENER Harry A. Toulmin, Jr., Dayton, Ohio, assignor to Chadeloid Corporation, Dayton, Ohio No Drawing. Application May 29, 1953,

Serial No. 358,553

6 Claims. (c1; 8-6.5)

This invention relates to stains, especially stains for use on wood and to compositions for use in staining wood articles and the like, as well as methods for staining such articles.

The art of wood staining in the past has made use of dyes which were dissolved or dispersed solvents and the like diluents so as to make the same applicable for applying as a spray, dip, or by brush. The water soluble stains generally consisted of an aqueous. solution of an aniline dye, and were applied by brushing the same on to the wood surface to be stained. Such water stains, however, exhibit the very undesirable effect of raising the grain of the wood. This raising of the grain necessitates that the surface be sanded or otherwise treated to render it smooth. The grain raising effect of such water soluble stains also makes it necessary to apply a sealer coating such as shellac to the stained wood in order to stiffen the.

fibers of the Wood so that the surfaces can be uniformly sanded. When an open-grain wood is used, it is necessary after the sanding operation to apply a filler to the surface over which is then applied a varnish, lacquer or other desired coating.

The non-aqueous stains, for example, oil stains and spirit stains, and which generally consist of an aniline dye or aniline dye base dissolved in an organic solvent such as a hydrocarbon or alcohol, have been extensively used and have certain advantages over water stains. They also have certain undesirable features. The use of hydrocarbons, such as benzol, toluol or other petroleum distillates that are highly volatile when applied to the surface to be treated tends to leave the pores of the wood unimpregnated with the dye. They are also dangerous in mass application in a furniture factory. Where such composition is applied to a wood surface having open grain, it has been the practice after drying to treat the surface with a filler. Again, before applying the finish coating of varnish or lacquer, there must be applied a coating of shellac or similar functioning coating over either the stain or the filler in order to prevent bleeding. This application of shellac or the like is necessary, otherwise the solvents of the varnish or lacquer will penetrate into the stain and cause the color to bleed into the finish coat. The use of hydrocarbon solvents also is undesirable from the standpoint of fire hazard and the eifect the volatile solvent may have on the operator applying the stain.

The spirit stains are not as useful as the water stains because they are subject to the disadvantage that such stains do not penetrate into the wood stains and they further lack permanency of color and tend to fade in use, similar as the oil type stains. Spirit stains are also subject to the bleeding effect, and in many instances, also produce the undesirable grain raising upon application to the wood surface.

and citrus waste, with aniline or aniline bases, and dis- I 'pe'rsing as by stirring, the resultant dye in water solution 2,723,898 Patented Nov. 15, 1955 that this new combination provides an excellent wood stain composition with unexpected results. This cltrus aniline dye compound can be readily fixed in the cellulose pores of the wood as it is derived from cellulose and is compatible with it. p

It may be applied as a hot or cold solution to the wood. A hot aqueous solution of such citrus-azo dyes as derived from these citrus fiavanone or glucosides obtained from citrus waste, being derived from a cellulose source, forms a stain which is completely compatible with the wood sothat a highly desirable stain effect is produced, with complete dispersion of uniform character and deep penetration.

The aqueous staining solutions of this invention which comprise the aforementioned citrus-azo dye are preferably applied as a hot aqueous solution, although it is also efiective as a Wood stain when applied as a. cold solution. Hot aqueous solutions of such dyes when applied penetrate into the wood and the solvent evaporates before the grain of the wood is caused to raise. Upon cooling, the dye is set in the wood and forms a smooth uniformly stained Wood surface which requires no sanding or other treatment to produce a desirable surface upon added which are luminescent in sunlight or effective to increase the brilliancy of the color. Other compatible water soluble dyes or pigments may be introduced in suitable amounts up to 10% of the weight of the citrus-azo dye to control the depth of the stain, grain development, and shade of the grain.

In particular, it is the object to either treat the wood before staining or treat the wood simultaneously with staining with so-called optical brighteners or sometimes called bleaches since these materials operate on the principle of converting ultraviolet or near ultraviolet light into a blue or near blue light. They serveas brighteners, whitening agents, optical bleaches and a screening agent for ultraviolet radiation. .They have the capacity of fluorescence and are capable of masking the normal yellowish forbrownish characteristics of cellulose and they have the capacity of producing contrasts between different colors and between diifeerent hues or shades thereby emphasizing the design asin the case of the grain of the wood as the grain of the wood reacts differently in color to stains and fillers than the remainder of the wood.

It has been a further problem to select these colorless dyes so that they would not conflict with the water-soluble aniline dyes of the non-grain raising stains and, additionally, select these brighteners so they would not conflict with oil-soluble stains when they are used in wood stains.

It is an additional problem to find a brightener that will produce the unexpected property of being both substantive to the water-soluble aniline stains and to cellulose of the wood. It was found desirable to select the luminous activator that would work satisfactorily with wood, the wood stain, the filler and any lacquer sealer and gloss lacquer used in Wood finishing and which would be undisturbed by the final rubbing and polishing operation of finishing wood. v

Heretofore, in the art, the problem has been two-fold in connection with wood stains: first, the aging of the wood finish in sunlight causing it to darken and the wood grain to lose its definition, depth, etc. This eliminated the natural contrast between the grain and the rest of the wood and depreciated the appearance of the wood, giving it a uniform dull, dark color. It has also been a problem in finishing wood not to over-finish it in that the multiple number of treatments such as filling, staining, sealing, lacquering, rubbing and polishing, while they built up, at the beginning of the life of the wood, a handsome appearance, yet, as the Wood aged, these multiple coatings also aged and became dull, in turn dulling the finishes of the wood.

The present invention has as its object to maintain over a long period of life the original appearance of the wood as it was just after it was finished, as well as to enhance that appearance initially by brightening the finish, bringing out the grain of the Wood and giving it that luminescent glow in sunlight that greatly enhances the beauty and quality of the wood.

It is also an object to place this brightening agent so that it would combine with the other dyes either when it had been put upon the wood and the wood was coated with these dyes to stain it or the brightening agent is put into the dye combination of the stain so that there is only one application. In either event, the result has been a marked improvement both in the initial appearance of the wood and in the subsequent life of the wood after finishing.

The optical brightening agents are usually water white and transparent and, therefore, have not interfered with the water soluble aniline dyes or oil soluble dyes used to stain the wood and they do not discolor the filler. When used they give the effect with the minimum of finishing operations of a highly finished piece of wood.

The optical brighteners which have been found useful are the coumarin derivatives, such as beta-methyl umbelliferone; the stilbene derivatives, derivatives of amino naphthalene and other brighteners that are colorless dyes, fluorescent, direct dyestuffs with an afiinity for cellulose. This gives to wood and Wood stains an increased surface reflectance and a more brilliant surface than an untreated surface. Other useful dyes are hydroxy coumarin; 1-naphthylamine-4-sulfonic acid, Na 2-naphthylamine-6, 8-disulfonate; dibenzylaminostilbene-sulfonic acid derivative; naphthalene; benzimidazole, such as 2-styryl benzimidazole or 1-(m-acetamido-2-benzimidazole)-2(p-acetamidophenyl) ethylene; triazine condensation products; 2,2'-ethylenebis (l-benzylbenzimidazole). For cellulose materials, the following have been found to be useful: o-alkoxy-benzoyl derivatives of 4,4-diamino-stilbene-2,2- disulfonic acid, and derivatives of 4,4'-diaminostilbene-2, and 2'-disulfonic acid.

We prefer B-methylumbelliferone which is a hydroxymethyl coumarin that is compatible with solvents, such as isopropanol or acetone. We may also employ styryl benzimidazole.

Another useful brightener is 4 methyl, 7 diethylamine coumarin.

It will be understood in the following examples that by a substitution of the following brighteners and the use of the solvents particularly applying to those brighteners that such substitutions can be made in the examples. For example, beta methyl umbelliferone is soluble in alcohols, ethers and esters and very slightly soluble in water. A typical product is that manufacture by Ciba, known as Uvitex RS. Ciba also manufactures Uvitex WS beta methyl umbelliferone which is soluble in alcohols, ethers, lacquer thinners and water and Uvitex W concentrate which is soluble in ethers, acetates, alcohols, ring hydrocarbons, water and esters. We find that the General Dyestull Companys Blancophor SC is a high concentrate styryl benzimidazole which is soluble in ethers but very slightly soluble in alcohol. We have found General Dyestuif Companys styryl benzimidazole, known as Blancophor R is very slightly soluble in ethers, alcohols and esters. General Dyestuff Companys Floral OB also may be used. It is understood that Floral OB, for instance, is a derivative of amino naphthalimid as covered by U. S. Patent No. 1,836,529.

In some instances the standard beta methyl umbelliferones were precipitated in stain solutions. In such an event, when placed in their proper solvent, they can be used to treat the wood before staining. They are not used in the stain, filler or finishing coats.

Amongst the most satisfactory of the foregoing types of compounds such as the umbelliferones is Uvitex WS or Uvitex RS, manufactured by Ciba Company, Inc., or paper white RB, manufactured by General Aniline and Film Corporation.

In this manner, the invention provides a wood staining composition which is very inexpensive and easy to manufacture, and wherein the use of expensive organic diluents and solvents and the like, with their attendant disadvantages may be entirely eliminated.

A typical formula of naringenin is as follows:

The combination citrus-azo dyes which are utilized in 0 forming the wood staining composition of this invention are exemplified by the following compounds which are illustrated graphically as follows:

Coupling aniline with naringenin, e. g. recovered from grapefruit waste, as described, results in the production of an azo dye having the probable structural formula:

Employing hesperetin, as recovered from orange waste, and coupling this compound with aniline, there results the production of an azo dye having the probable structural formula:

In accordance with the present invention, I have found that these azo dyestuffs can be obtained by coupling a diazotized aromatic amino compound, preferably one containing at least one substituted benzene nucleus or a oxy-naphthalene nucleus, with a flavanone, naringenin, eriodictyol or hesperetin, such as derived from citrus waste products. The resultant dyestuffs, which are water soluble, are of particular value in compounding wood stains.

The object of coupling into a new compound of the naringenin and hesperetin with a diazotized aromatic amino compound to produce a carrier on which the dye compound may'be fixed in suitable colors of the browns, yellows and reds of varying hues and shades.

These citrus dyes are soluble in methanol to a limited about 10 to 15 minutes a 0.1 mol sodium nitrite.

degree and are very slightly soluble in carbitol cellusolve. They are insoluble in hydrocarbons, esters and higher alcohols. Higher temperatures do not increase solubility in solvents.

Therefore, the advantage lies in the fact that the dyes being insoluble in the customary solvents, it is possible to provide a rapidly volatizing organic solvent in which the dye is substantially soluble; and to provide a wood stain that, when it is once applied, is not subject to injury by the hydrocarbons, esters, alcohols, etc. The Water solution of the dye, therefore, maintains its integrity despite the association with it in application of rapidly volatizing organic solvents or in use with glycols, ethers, alcohols and the benzene series of hydrocarbons.

These dyes stained the wood well, with good clarity and non-bleeding into succeeding coats. The darker dyes are more soluble than the red dyes. The darker dyes can be made in as high as a ten ounce solution as contrasted with the usual two ounce solution in the lighter dyes.

Illustrative of the method of producing the diazo dyes for use in preparing aqueous wood stains is as follows:

Example I 1. To a slurry comprising 0.1 mol of aniline in water is added 0.25 mol of hydrochloric acid. The mixture is diluted with water and cooled to a temperature of between about -15" C.

While maintaining the temperature of the mixture at about 10 C. there is added slowly over a period of The mixture is stirred slowly while maintaining the temperature at about 10 C. for one-half an hour.

2. To effect the coupling reaction, a solution containing 0.1 mol of hesperetin dispersed in an aqueous solution containing 0.3 mol of sodium hydroxide is employed. The mixture is diluted with water and cooled to between and C. Thereafter, the azo dye solution of (1) is stirred into the mixture over a minute period while maintaining the temperature at about 10-15" C. and the pH of the solution above 9. After stirring the mixture for half an hour more the dyestuif is isolated by adjusting the pH of the solution to neutral with diluted hydrochloric acid and adding a salt, i. e., sodium chloride or sodium sulfate, until the dye precipitates from the solution. Thereafter, the mixture is filtered to recover the dyestufi.

Example 11 In this example, aniline is diazotized in the usual manner and coupled with naringenin (or a mixture of naringenin and hesperetin) as the glucoside substance, and to the foregoing is added from one part in a thousand to one part in ten thousand of an optical brightener (beta methyl umbelliferone).

Example 111 Variations of naringenin azo dyestuffs are made by carrying out the coupling as described in Example I employing other amines or amino compounds in place of aniline, such as l-naphthamine 4 sulphonic acid, 2 amino 8 naphthol sulfonic acid and p-nitroaniline, and to the foregoing is added from one part in a thousand to one part in ten thousand of an optical brightener (4, methyl 7-diethylamine coumarin).

Example I V Similarly variations of hesperetin azo dyestuffs are prepared by etfecting a coupling action as described in Example I utilizing instead of aniline, other amino compounds such as l-naphthalene 4-sulfonic acid, 2-amino S-naphthol 6-sulfonic acid.

The invention broadly includes the preparation of wood staining compositions comprising a water-soluble azo dyestuif containing the grouping in which A represents the residue of an aromatic amino compound, N is nitrogen and B is a glucoside of flavanone derivative of citrus waste as described above, and to the foregoing is added from one part in a thousand to one part in ten thousand of an optical brightener (steryl benzimidazole Varied shades of color may be produced with the citrus azo dyestuffs, depending on the particular amine and glucoside usedin compounding the dyestufi.

The following examples are exemplary of the specific wood staining compositions in accordance with the present invention:

Example V A wood stain is prepared by dissolving the product of Example I in water to form a 5% solution. The resulting stain may be applied to wood by brushing or spraying.

Example VI To a gallon of water is added one ounce of the dyestuff prepared as described in Example I.

Example VII Suitable amounts of the dyestuffs, as described in Examples III and IV, are dissolved in water to provide a staining composition having the desired strength.

The amount of dye utilized in a given case depends upon the particular dye employed, and its degree of concentration and, of course, the depth of color required for the particular stain.

A combination citrus-azo dye stain and filler having a transparent color that is fast to light, may accordingly be produced under this disclosure, whereas this result has never heretofore been possible.

In accordance with the present invention, it is possible for the first time to utilize such Water soluble azo dyes made by coupling a flavanone derivative, such as naringenin, eriodictyol or hesperetin with aniline or other suitable azotizing amino compound to form a water soluble dye which yields, upon dispersion in an aqueous vehicle, a wood stain which is substantially fast to light, and exhibits non-fading, non-grain raising properties. A wood stain also is provided, which when properly compounded and applied as described, does not bleed through lacquer or varnish top finishing coats. Thus, the use of intermediate sealing coats is not necessary. Where desired, of course, intermediate sealing coats of suitable type may be employed.

This application relates to applicants prior application Serial Number 277,920, filed March 21, 1952.

It will be understood that while there have been described herein certain specific embodiments of this invention, it is not intended thereby to have it limited to or circumscribed by the specific details given in View of the fact that this invention is susceptible to various modifications and changes which come within the spirit of this disclosure and the scope of the appended claims.

I claim:

1. A wood staining composition comprising an azo dye in which the coupling component is chosen from the group consisting of naringenin, hesperetin, and eriodictyol, said composition containing water and a brightening agent.

2. A wood staining composition as in claim 1, in which the azo dye consist of diabotized aniline coupled with a component chosen from the group consisting of naringenin, hesperetin, and eriodictyol.

3. A wood staining composition comprising an azo dye in which the coupling component is chosen from the group consisting of naringenin, hesperetin and eriodictyol, said composition containing a filler, water and a brightening agent.

4. A wood staining composition comprising an azo dye in which the coupling component is naringenin, said composition containing water and a brightening agent.

7 5. A wood staining composition comprising an azo dye in which the coupling component is hesperetin, said composition containing Water and a brightening agent.

6. A wood staining composition comprising an azo dye in which the coupling component is eriodictyol, said com position containing water and a brightening agent.

References Cited in the file of this patent UNITED STATES PATENTS 901,096 Hall Oct. 13, 1908 8 Chapin Aug. 11, 1914 Moore Oct. 16, 1934 Bush May 7, 1935 Moore Jan. 18, 1938 Axelrad Feb. 8, 1944 FOREIGN PATENTS Great Britain Mar. 22, 1944 OTHER REFERENCES Perkin, Jour. Chem. Soc., vol. 73 (1898), pp. 666-674. 

1. A WOOD STAINING COMPOSITION COMPRISING AN AZO DYE IN WHICH THE COUPLING COMPONENT IS CHOSEN FROM THE GROUP CONSISTING OF NARINGENIN, HESPERETIN, AND ERIODICTYOL, SAID COMPOSITION CONTAINING WATER AND A BRIGHTENING AGENT. 